The present invention relates to a flame retardant for thermoplastic resins and a flame retardant resin composition.
Thermoplastic resins have been widely used in electric and electronic parts, office automation devices, household articles and building materials. However, thermoplastic resins have the defect that they are generally inflammable. Therefore, the improvement has been attempted by incorporation of various flame retardants. For instance, incorporation of organic halogen-containing compounds or organic phosphorus compounds has been widely conducted for this purpose. However, most of the organic halogen-containing compounds and organic phosphorus compounds have a problem in toxicity. In particular, organic halogen-containing compounds have the problem that they generate a corrosive gas at the time of burning.
In order to solve these problems, it has been investigated to impart a flame resistance by incorporation of polyorganosiloxane compounds (hereinafter also referred to as xe2x80x9csiliconexe2x80x9d). For example, Japanese Patent Publication Kokai No. 54-36365 discloses that a flame retardant resin is obtained by kneading a non-silicone polymer with a silicone resin composed of monoorganopolysiloxane.
Japanese Patent Publication Kokoku No. 3-48947 discloses that a mixture of a silicone resin and a salt of a group IIA metal imparts a flame retardancy to thermoplastic resins.
Japanese Patent Publication Kokai No. 8-113712 discloses a process for obtaining a flame retardant resin composition by dispersing into thermoplastic resins a silicone resin prepared by mixing 100 parts by weight of a polyorganosiloxane with 10 to 150 parts by weight of a silica filler.
Japanese Patent Publication Kokai No. 10-139964 discloses that a flame retardant resin composition is obtained by incorporating a solvent-soluble silicone resin having a weight average molecular weight of 10,000 to 270,000 into a non-silicone resin containing an aromatic ring.
However, although the silicone resins disclosed in the above publications impart a flame retardancy to some extent, they lower the impact resistance of resin compositions if incorporated in an excess amount and, therefore, it has been difficult to obtain flame retardant resin compositions having well-balanced flame resistance and impact resistance.
It is an object of the present invention to provide a flame retardant of low environmental load which does not generate a harmful gas when burns.
A further object of the present invention is to provide a flame retardant thermoplastic resin composition of low environmental load which does not generate a harmful gas when burns and which has an excellent impact resistance.
The resent inventors have found, as a result of making an intensive study in order to achieve the above objects, that crosslinked particles of a specific polyorganosiloxane can be used as a flame retardant for thermoplastic resins, and thermoplastic resin compositions containing the polyorganosiloxane crosslinked particles are excellent not only in flame resistance but also in impact resistance.
The present invention provides a flame retardant for thermoplastic resins comprising crosslinked particles of a polyorganosiloxane which have a toluene-insoluble matter content of at least 50% by weight and an average particle size of 0.01 to 2,000 xcexcm.
Preferably, the polyorganosiloxane crosslinked particles are prepared by emulsion polymerization of a mixture of 50 to 99.5% by weight, especially 60 to 98.5% by weight, of an organosiloxane and/or a difunctional silane compound, 0.5 to 50% by weight, especially 0.5 to 39% by weight, of a silane compound having a functionality of at least 3, and 0 to 40% by weight, especially 0.5 to 30% by weight, of a polymerizable vinyl group-containing silane compound.
Further, the present invention provides a flame retardant resin composition comprising a thermoplastic resin and 0.1 to 50 parts by weight of the above-mentioned flame retardant per 100 parts by weight of the thermoplastic reisn.
The flame retardant for thermoplastic resins of the present invention comprises crosslinked particles of a polyorganosiloxane which have a toluene-insoluble matter content of not less than 50% by weight and an average particle size of 0.01 to 2,000 xcexcm.
The term xe2x80x9cpolyorganosiloxanexe2x80x9d as used herein indicates a polyorganosiloxane, a modified polyorganosiloxane wherein 1 to 20% by weight, preferably 1 to 10% by weight, of a polyorganosiloxane is replaced with an organic polymer having no polyorganosiloxane segment (e.g., butyl acrylate polymer, styrene-butyl acrylate copolymer, styrene-acrylonitrile copolymer, or methyl methacrylate polymer), and the like. The modified polyorganosiloxane includes a modified polyorganosiloxane wherein a polyorganosiloxane and an organic polymer having no polyorgaosiloxane segment are chemically bonded, and a modified polyorganosiloxane wherein a polyorganosiloxane and an organic polymer having no polyorgaosiloxane segment are merely coexist. The content of the organic polymer in the modified polyorganosiloxane is not more than 20% by weight, preferably not more than 10% by weight.
The content of toluene-insoluble matter in the polyorganosiloxane crosslinked particles measured by immersing 0.5 g of the crosslinked particles in 80 ml of toluene at room temperature for 24 hours is from 50 to 100% by weight, preferably 60 to 100% by weight. Also, the average particle size of the crosslinked particles obtained by a light scattering method or electron microscopic observation is from 0.01 to 2,000 xcexcm, preferably from 0.01 to 1,000 xcexcm. If the content of toluene-insoluble matter is small, the flame resistance-impact resistance balance tends to be deteriorated. If the average particle size is too small or too large, the flame resistance-impact resistance balance tends to be deteriorated.
It is preferable from the viewpoint of good flame resistance-impact resistance balance that the variation coefficient in particle size distribution of the above-mentioned average particle size (100xc3x97standard deviation/average particle size (%)) is from 10 to 100%, especially 20 to 80%. It is difficult to obtain the particles having a variation coefficient of less than 10%. If the variation coefficient is too large, the flame resistant effect tends to be lowered.
The polyorganosiloxane crosslinked particles can be prepared, for instance, by polymerizing a polyorganosiloxane-forming component comprising (a) an organosiloxane and/or a difunctional silane compound, (b) a silane compound having a functionality of at least 3, and optionally (c) a polymerizable vinyl group-containing silane compound. Preferably, the polyorganosiloxane crosslinked particles is prepared by polymerizing, for instance, a polyorganosiloxane-forming component comprising (a-1) an organosiloxane having an aromatic group and/or a difunctional silane compound having an aromatic group, (a-2) an organosiloxane having no aromatic group and/or a difunctional silane compound having no aromatic group, (b) a silane compound having a functionality of at least 3, and (c) a polymerizable vinyl group-containing silane compound.
The component (a-1) serves to impart a flame resistance. As the component (a-1) is used at least one member selected from the group consisting of organosiloxanes having an aromatic group and difunctional silane compounds having an aromatic group. Examples of such an organosiloxane are, for instance, cyclic siloxanes such as trimethyl-triphenylcyclotrisiloxane and tetramethyltetraphenylcyclotetrasiloxane. Examples of the difunctional silane compound are, for instance, diphenyldimethoxysilane, diphenyldiethoxysilane, diphenyldichloro-silane, phenylmethyldimethoxysilane, phenylmethyldichlorosilane, and the like. Of these, diphenyldimethoxysilane and diphenyldichlorosilane are preferably used from the viewpoints of economy and reactivity.
The component (a-2) constitutes the main backbone of polyorganosiloxane chain, and as the component (a-2) is used at least one member selected from the group consisting of organosiloxanes having no aromatic group and difunctional silane compounds having no aromatic group. Examples of such an organosiloxane are, for instance, a cyclic siloxane such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane or dodecamethylcyclohexasiloxane, a linear organosiloxane oligomer, and the like. Examples of the difunctional silane compound having no aromatic group are, for instance, diethoxydimethylsilane, dimethoxydimethylsilane, 3-chloropropylmethyldimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, heptadecafluorodecylmethyl-dimethoxysilane, trifluoropropylmethyldimethoxysilane, octadecyl-methyldimethoxysilane, and the like. Of these, octamethyl-cyclotetrasiloxane and mixtures of at least two cyclic siloxanes are preferred from an economical point of view.
The silane compound (b) having a functionality of at least 3 is used to introduce a crosslinked structure by the copolymerization with the components (a-1) and (a-2), thereby imparting a rubber elasticity to the polyorganosiloxane, while causing to produce incombustibles. Examples thereof are, for instance, tetrafunctional and trifunctional alkoxysilane compounds such as tetraethoxysilane, methyltriethoxysilane, methyltrimethoxysilane, ethyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, trifluoropropyltrimethoxysilane, octadecyltrimethoxysilane and phenyltriethoxysilane, and others. Of these, tetraethoxysilane, methyltriethoxysilane, methyltrimethoxysilane and phenyltrimethoxy-silane are preferred from the viewpoint of being effective in flame retardation.
The polymerizable vinyl group-containing silane compound (c) is a component for introducing polymerizable vinyl groups into the side chains or molecular chain ends of copolymers by the copolymerization with the components (a-1), (a-2) and (b) and the like. The polymerizable vinyl group serves to raise the dispersibility of the crosslinked particles into thermoplastic resins. Further, the polymerizable vinyl group serves as a crosslinking point which forms crosslinkages by a radical reaction between the polymerizable vinyl groups through a radical polymerization initiator as used in usual radical polymerization, and serves as a grafting point when grafting a vinyl monomer.
Examples of the polymerizable vinyl group-containing silane compound (c) are, for instance, a silane comound of the formula (I): 
wherein R1 is hydrogen atom or methyl group, R2 is a monovalent hydrocarbon group having 1 to 6 carbon atoms, X is an alkoxyl group having 1 to 6 carbon atoms, a is 0, 1 or 2, and p is an integer of 1 to 6, a silane compound of the formula (II): 
wherein R2, X and a are as defined above, and q is 0 or an integer of 1 to 6, a silane compound of the formula (III): 
wherein R2, X and a are as defined above, a silane compound of the formula (IV): 
wherein R2, X and a are as defined above, and R3 is a bivalent hydrocarbon group having 1 to 6 carbon atoms, a silane compound of the formula (V): 
wherein R2, X and a are as defined above, and R4 is a bivalent hydrocarbon group having 1 to 18 carbon atoms, and the like.
Examples of the group R2 in the formulas (I) to (V) are, for instance, an alkyl group such as methyl group, ethyl group or propyl group, phenyl group, and the like. Examples of the group X are, for instance, methoxy group, ethoxy group, propoxy group and butoxy group and the like. Examples of the group R3 in the formula (IV) are, for instance, methylene group, ethylene group, propylene group butylene group and the like. Examples of the group R4 in the formula (V) are, for instance, methylene group, ethylene group, propylene group butylene group and the like.
Examples of the silane compound (I) are, for instance, xcex2-methacryloyloxyethyldimethoxymethylsilane, xcex3-methacryloyloxypropyl-dimethoxymethylsilane, xcex3-methacryloyloxypropyltrimethoxysilane, xcex3-methacryloyloxypropyldimethylmethoxysilane, xcex3-methacryloyloxypropyltriethoxysilane, xcex3-methacryloyloxypropyldiethoxymethylsilane, xcex3-methacryloyloxypropyltripropoxysilane, xcex3-methacryloyloxypropyldipropoxymethylsilane, xcex3-acryloyloxypropylmethyldimethoxysilane, xcex3-acryloyloxypropyltrimethoxysilane, and the like. Examples of the silane compound (II) are, for instance, p-vinylphenyldimethoxymethylsilane, p-vinylphenyltrimethoxysilane, p-vinylphenyltriethoxysilane, p-vinylphenyldiethoxymethylsilane, and the like. Examples of the silane compound (III) are, for instance, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, and the like. Examples of the silane compound (IV) are, for instance, allylmethyldimethoxysilane, allylmethyldiethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, and the like. Examples of the silane compound (V) are, for instance, mercaptopropyltrimethoxysilane, mercaptopropyldimethoxymethylsilane, and the like. Of these, silane compounds of the formulas (I), (II) and (V) are preferably used from the economical point of view.
In case that the above-mentioned polymerizable vinyl group-containing silane compounds (c) are of trialkoxysilane type, they also serve as a crosslinking agent. Also, in case of using the component (c), it is preferable to use it in an amount of at least 0.5% by weight so as to exhibit its effect.
With respect to the proportions of the components (a-1), (a-2), (b) and (c) in the polyorganosiloxane-forming component in the polymerization thereof, it is preferable that the proportion of the component (a-1) is from 0.5 to 70% by weight, especially 2 to 70% by weight, more especially 5 to 70% by weight, the proportion of the component (a-2) is from 29.5 to 99% by weight, especially 29 to 96.5% by weight, more especially 25 to 90% by weight, the proportion of the silane compound (b) having a functionality of at least 3 is from 0.5 to 50% by weight, especially 0.5 to 39% by weight, more especially 3 to 29% by weight, and the proportion of the polymerizable vinyl group-containing silane compound (c) is from 0 to 40% by weight, especially 0.5 to 30% by weight, more especially 2 to 20% by weight. In each of the components (a-1) and (a-2), the ratio of the organosiloxane to the difunctional silane compound is usually from 100/0 to 0/100 by weight, especially from 98/2 to 40/60 by weight.
If the proportion of the component (a-1) is too small, the obtained crosslinked particles tend to exhibit the flame resistance-imparting effect with difficulty. If the proportion of the component (a-1) is too large, the cost tends to increase. If the proportion of the component (a-2) is too small, the cost tends to increase, and if the proportion of the component (a-2) is too large, the flame resistance tends to lower. If the proportion of the component (b) is too small or too large, the balance between the flame retardation effect and the impact resistance-imparting effect of the obtained crosslinked particles tends to be deteriorated. The component (c) is an optional component. If the proportion thereof exceeds 40% by weight, the flame resistance-improving effect of the crosslinked particles tend to be exhibited with difficulty.
Preferably, the polyorganosiloxane crosslinked particles are prepared by emulsion-polymerizing the polyorganosiloxane-forming component comprising the components (a-1), (a-2) and (b) and optionally the component (c).
The emulsion polymerization can be carried out by known methods, for example, as disclosed in U.S. Pat. Nos. 2,891,920 and 3,294,725.
For example, the polyorganosiloxane-forming component is emulsified and dispersed into water by mechanical shearing in the presence of an emulsifier and the obtained emulsion can be subjected to polymerization under an acidic condition. In case that emulsified droplets having a size of not less than several micrometers have been produced by mechanical shearing, it is possible to control the average particle size of the polyorganosiloxane particles obtained after the polymerization within the range of 0.02 to 0.5 xcexcm depending on the amount of an emulsifier used. It is also possible to obtain the particles whose variation coefficient (100xc3x97standard deviation/average particle size) in the particle size distribution of which is not more than 70%.
Also, when it is desired to prepare polyorganosiloxane particles having an average particle size of not more than 0.1 xcexcm and a narrow particle size distribution, it is preferable to carry out the polymerization in multistages. For example, 1 to 20% by weight of an emulsion comprising emulsified droplets of not less than several micrometers obtained by emulsifying the polyorganosiloxane-forming component, water and emulsifier by means of mechanical shearing thereof is previously subjected to emulsion polymerization under an acidic condition, and the remaining emulsion is then added and polymerized in the presence of the produced polyorganosiloxane as seeds. In case of preparing the polyorganosiloxane particles in such a manner, it is possible to control the average particle size within the range of 0.02 to 0.1 xcexcm depending on the amount of an emulsifier used, and also to control the variation coefficient in the particle size distribution to not more than 60%. More preferable is a multistage polymerization method wherein a vinyl (co)polymer prepared by homo- or copolymerizing a vinyl monomer such as styrene, butyl acrylate or methyl acrylate in a usual emulsion polymerization manner is used as seeds instead of the previously produced polyorganosiloxane in the above multisatge polymerization, and a multistage polymerization is carried out in the same manner as above. According to such a method, it is possible to control the average particle size of the obtained polyorganosiloxane particles (modified polyorganosiloxane particles) within the range of 0.01 to 0.1 xcexcm, and the variation coefficient in the particle size distribution to not more than 50% depending on the amount of an emulsifier used.
The variation coefficient in the particle size distribution of the polyorganosiloxane crosslinked particles obtained by these methods is preferably from 10 to 100%, more preferably from 20 to 80%, from the viewpoint of good flame resistance-impact resistance balance.
The emulsion droplets of not less than several micrometers can be prepared by using a high speed agitating machine such as a homomixer.
In the above-mentioned emulsion polymerization are used emulsifiers which do not lose an emulsifying ability under an acidic condition. Examples of the emulsifier are, for instance, alkylbenzenesulfonic acid, sodium alkylbenzenesulfonate, alkylsulfonic acid, sodium alkylsulfonate, sodium (di)alkyl sulfosuccinate, sodium polyoxyethylene nonylphenyl ether sulfonate, sodium alkylsulfate, and the like. These may be used alone or in admixture thereof. Of these, from the viewpoint of a relatively high effect of stabilizing the emulsion, preferred are alkylbenzenesulfonic acid, sodium alkylbenzenesulfonate, alkylsulfonic acid, sodium alkylsulfonate, sodium (di)alkyl sulfosuccinate and benzylmethyldodecyl ammonium hydroxide. Further, alkylbenzenesulfonic acid and alkylsulfonic acid are particularly preferred since they also serves as a polymerization catalyst for the polyorganosiloxane-forming component.
The acidic condition is adjusted by adding an inorganic acid such as sulfuric acid or hydrochloric acid or an organic acid such as alkylbenzenesulfonic acid, alkylsulfonic acid or trifluoroacetic acid to the reaction system. The pH of the system is preferably from 1.0 to 3, more preferably from 1.2 to 2.5, from the viewpoints of corrosion of a plant and adequate rate of polymerization.
The polymerization temperature is preferably from 60 to 120xc2x0 C., more preferably from 70 to 100xc2x0 C., since the polymerization velocity is adequate.
Under an acidic condition, the Sixe2x80x94Oxe2x80x94Si bond which constitutes the polyorganosiloxane backbone is in an equilibrium state between severance and formation, and this equilibrium varies depending on the temperature. For the purpose of stabilization of polyorganosiloxane chains, it is preferable to neutralize by addition of an aqueous solution of an alkali such as sodium hydroxide, potassium hydroxide or sodium carbonate. The equilibrium shifts to the formation side as the temperature lowers and, therefore, a polyorganosiloxane having a high molecular weight or a high degree of crosslinking is easy to be produced. Thus, when it is desired to obtain a polyorganosiloxane having a high molecular weight or a high degree of crosslinking, it is preferable that after conducting the polymerization of a polyorganosiloxane-forming component at a temperature of 60xc2x0 C. or higher, the reaction mixture is cooled to room temperature or lower, maintained at that temperature for 5 to 100 hours and then neutralized.
Thus, an emulsion containing crosslinked particles of polyorganosiloxane is obtained. The polyorganosiloxane crosslinked particles, for example, when formed from the components (a-1), (a-2) and (b), have a network structure wherein usually these components are copolymerized at random and crosslinked. When the component (c) is further copolymerized, the polyorganosiloxane crosslinked particles have a crosslinked structure having polymerizable vinyl groups. Further, when the polymerizable vinyl groups are reacted to form crosslinkages between them by a radical reaction by means of a radical polymerization initiator, there are obtained those having a crosslinked structure wherein the polymerizable vinyl groups are chemically bonded to each other. The polyorganosiloxane crosslinked by radical reaction is preferable, since the polyorganosilixane particles are easy to handle when recovered from the emulsion.
The radical reaction can be conducted without particular restriction, for example, by a method wherein a radical polymerization initiator is added to the emulsion and the reaction is caused to proceed by thermally decomposing the initiator, or a method wherein the reaction is caused to proceed in a redox system using a reducing agent.
Examples of the radical polymerization initiator are an organic peroxide such as cumene hydroperoxide, tert-butyl hydroperoxide, benzoyl peroxide, tert-butylperoxy isopropylcarbonate, di-tert-butyl peroxide, tert-butylperoxy laurate or lauroyl peroxide; an inorganic peroxide such as potassium persulfate or ammonium persulfate; an azo compound such as 2,2xe2x80x2-azobisisobutylonitrile or 2,2xe2x80x2-azobis-2,4-dimethylvaleronitrile; and the like. Of these, organic peroxides and inorganic peroxides are preferably used from the viewpoint of a high reactivity.
Examples of the reducing agent used in the redox system are a mixture of ferrous sulfate/glucose/sodium pyrophosphate, a mixture of ferrous sulfate/dextrose/sodium pyrophosphate, a mixture of ferrous sulfate/sodium formaldehyde sulfoxylate/ethylenediamineacetate, and the like.
It is preferable that the radical polymerization initiator is used usually in an amount of 0.005 to 20 parts by weight, especially 0.01 to 10 parts by weight, more especially 0.03 to 5 parts by weight, per 100 parts by weight of the polyorganosiloxane-forming component used. If the amount of the initiator is less than 0.005 part by weight, the rate of reaction is low, so the production efficiency tends to be lowered, and if the amount is more than 20 parts by weight, heat generation during the reaction becomes large, so the production tends to become difficult.
The temperature in the radical reaction is preferably from 30 to 120xc2x0 C., more preferably from 40 to 100xc2x0 C., from the viewpoints of stability of the reaction system and production efficiency.
Further, so long as the content of the polyorganosiloxane component in the obtained polyorganosiloxane crosslinked particles is adjusted to not less than 80% by weight, peferably not less than 90% by weight, at least one vinyl monomer such as styrene, acrylonitrile, methyl methacryate, butyl methacrylate or glycidyl methacrylate can be graft-polymerized to the crosslinked polyorganosiloxane. If an adequate amount of a graft component compatible with thermoplastic resins as mentioned after is present, dispersion of the polyorganosiloxane crosslinked particles into the thermoplastic resins becomes good, so it is possible to raise the impact resistance. However, since the presence of the graft component tends to lower the flame resistance, it is preferable to adjust the content of the polyorganosiloxane component so as not to be less than 80% by weight.
Recovery of the polyorganosiloxane crosslinked particles in the form of a powder from emulsions of the polyorganosiloxane crosslinked particles obtained by emulsion polymerization is carried out by a conventional method, for example, by adding to the aqueous emulsion a metal salt such as calcium chloride, magnesium chloride or magnesium sulfate or an inorganic or organic acid such as hydrochloric acid, sulfuric acid, phosphoric acid or acetic acid to coagulate the emulsion, followed by washing with water or hot water, dehydration and drying of the deposited polymer. A spray drying method is also applicable.
The crosslinked particles agglomerate to increase the particle size when a solid powder is recovered from the emulsion, thus giving a powder having an average particle size of 0.01 to 2,000 xcexcm, especially 0.01 to 1,000 xcexcm. The variation coefficient in the particle size distribution is preferably from 10 to 100%, more preferably from 20 to 80%.
The thus obtained polyorganosiloxane crosslinked particles (in the form of a solid powder or an emulsion) provide thermoplastic resin compositions having an excellent flame resistance-impact resistance balance by the incorporation into thermoplastic resins.
Examples of the thermoplastic resin are, for instance, acrylonitrile-styrene copolymer, acrylonitrile-butadiene rubber-styrene copolymer (ABS resin), acrylonitrile-butadiene rubber-xcex1-methylstyrene copolymer, styrene-butadiene rubber-acrylonitrile-N-phenylmaleimide copolymer, acrylonitrile-acrylic rubber-styrene copolymer (AAS resin), acrylonitrile-acrylic rubber-xcex1-methylstyrene copolymer, styrene-acrylic rubber-acrylonitrile-N-phenylmaleimide copolymer, acrylonitrile-ethylenepropylene rubber-styrene copolymer (AES resin), polycarbonate, polyester such as polyethylene terephthalate or polybutylene terephthalate, polyvinyl chloride, polypropylene, polyphenylene ether, polystyrene, polymethyl methacrylate, methyl methacrylate-styrene copolymer, polyamide, and the like. These may be used alone or in admixture thereof.
It is preferable, from the viewpoint of a balance of physical properties, that the amount of the polyorganosiloxane crosslinked particles is from 0.1 to 50 parts by weight, especially from 1 to 30 parts by weight, per 100 parts by weight of a thermoplastic resin. If the amount is too small, no effect of the addition is obtained, and if the amount is too large, it is difficult to maintain the properties such as rigidity and surface hardness of the thermoplastic resins.
Mixing of a thermoplastic resin with a solid powder of the polyorganosiloxane crosslinked particles isolated from the emulsion as mentioned above can be carried out by firstly mixing them through a Henschel mixer, a ribbon mixer or the like and then melt-kneading the mixture through a roll mill, an extruder, a kneader or the like.
The thermoplastic resin composition can also be obtained by mixing an emulsion of a thermoplastic resin with an emulsion of the polyorganosiloxane crosslinked particles and subjecting the mixed emulsion to coprecipitation of polymer particles.
The thermoplastic resin compositions of the present invention may contain usual additives, e.g., plasticizer, stabilizer, lubricant, ultraviolet absorber, antioxidant, known flame retardant, pigment, glass fiber, filler, high molecular processing aid, high molecular lubricant, impact modifier and antisagging agent. Preferable examples of the high molecular processing aid are, for instance, methacrylate (co)polymers such as methyl methacrylate-butyl acrylate copolymer. Preferable examples of the impact modifier are, for instance, MBS resin, acrylic rubber-containing graft copolymer and graft copolymer containing composite rubber of acrylic rubber and silicone rubber. Preferable examples of the antisagging agent are, for instance, fluorocarbon resin such as polytetrafluoroethylene.
Molding methods conventionally used for thermoplastic resin compositions, e.g., injection molding, extrusion, blow molding and calendering, are applicable to the thermoplastic resin compositions of the present invention.
The obtained molded articles have excellent properties such as flame resistance and impact resistance.
The present invention is more specifically explained by means of examples, but it is to be understood that the present invention is not limited to only these examples. In the examples, all parts and % excepting variation coefficient are by weight unless otherwise noted.
In the following examples and comparative examples, measurement and evaluation were made in the following manners.
[Polymerization Conversion]
An emulsion was dried in a hot air dryer at 120xc2x0 C. for 1 hour to measure the content of solid matter of a polyorganosiloxane. The polymerization conversion was calculated according to the equation: (solid matter content/amount of monomers charged)xc3x97100 (%).
[Content of Toluene-insoluble Matter]
In 80 ml of toluene was immersed 0.5 g of the polyorganosiloxane crosslinked particles obtained from an emulsion by drying it at room temperature for 24 hours, and it was centrifuged at 12,000 r.p.m. for 60 minutes to measure the content (% by weight) of the toluene-insoluble matter in the polyorganosiloxane crosslinked particles.
[Average Particle Size]
Average particle size of an emulsion of polyorganosiloxane crosslinked particles:
Using a measuring apparatus, NICOMP MODE L370 Particle Size Analyzer made by PACIFIC SCIENTIFIC CO., the volume average particle size (xcexcm) and the variation coefficient in particle size distribution (standard deviation/volume average particle size)xc3x97100 (%) were measured by a light scattering method.
Average Particle Size of Solid Powder
Using a measuring apparatus, MICROTRAC FRA made by LEED and NORTHRUP INSTRUMENTS, the volume average particle size (xcexcm) and the variation coefficient in particle size distribution (standard deviation/volume average particle size)xc3x97100 (%) were measured by a light scattering method.
[Izod Impact Strength]
The Izod impact strength was measured at 23xc2x0 C. by using a notched xc2xc inch bar or a notched xe2x85x9 inch bar according to ASTM D-256.
[Flame Resistance]
Evaluation was made by UL94 V test or UL94 HB test.
[Surface Appearance]
The test specimen used in the evaluation of flame resistance was visually observed and the surface appearance was evaluated according to the following criteria.
◯: The surface state is good.
xcex94: A stripe pattern is observed in the surface.
xc3x97: A stripe pattern and peeling are observed in the surface.
The raw materials used are shown below.
PC: Polycarbonate, TOUGHRON A-2200 made by Idemitsu Sekiyu Kagaku Kabushiki Kaisha
PET: Polyethylene terephthalate, BELPET EFG-70 made by Kanebo, Ltd.
PBT: Polybutylene terephthalate, CELANEX 1600A made by Hoechst Celanese Corp.
PTFE: Polytetrafluoroethylene, POLYFLON FA-500 made by Daikin Industries, Ltd.
AAS: AAS resin prepared in Example 9
Si-1: Polyorganosiloxane crosslinked particles prepared in Example 1
Si-2: Polyorganosiloxane crosslinked particles prepared in Example 2
Si-3: Polyorganosiloxane crosslinked particles prepared in Example 3
Si-4: Polyorganosiloxane crosslinked particles prepared in Example 4
Sixe2x80x2-1: Crosslinked polyorganosiloxane prepared in Com. Ex. 1
Sixe2x80x2-2: Linear polyorganosiloxane prepared in Com. Ex. 2